1. Field of the Invention
The present invention relates to an automatic rotating-type turret device used for work machinery such as a vertical lathe.
2. Description of the Related Art
Automatic rotating-type turret devices, in which a plurality of tools are provided on a turret, wherein the tool in use is switched from one to another by rotation, and the turret is automatically caused to rotate relative to a turret stage when tools are being switched, generally have the following configuration (a description will be given with reference to drawings of the present embodiment and using keys that are identical to those of the equivalent sections in the present embodiment).
The automatic rotating-type turret device is configured so that a turret 3 having a plurality of tools (a plurality of blade tools 21 exchangeably provided to each of a plurality of holders 20) is rotatably fitted on a rotation shaft portion 2 protrudingly fixed on a turret stage 1; a clutch device 4 is provided along the rotation shaft portion 2 so as to be capable of sliding in either direction, wherein the turret 3 is locked by the clutch device 4 in an indexing position so that the turret can be locked or unlocked in the indexing position by sliding in the direction of the rotation shaft; is caused to slide from a base end portion to a distal end portion to unlock the clutch device 4 whereupon the turret 3 becomes capable of rotating; and is caused to slide in the return direction at the indexing position after rotation so as to be locked by the clutch device 4 (i.e., the clutch is engaged) so as to be no longer capable of rotating.
Specifically, the automatic rotating-type turret device is configured so that a rotation gear portion that engages with a transmission gear driven by an indexing rotation drive device is provided to the turret 3; a clutch locking portion used as the clutch device 4 is provided to the turret stage 1; and a clutch engaging portion for detently and matingly engaging with the clutch locking portion is provided to the base end portion of the turret 3. The clutch locking portion and the clutch engaging portion disengage from each other and the turret 3 becomes capable of rotating when it slides from the base end portion to the distal end portion; and the indexing rotation drive device causes the turret 3 to be indexed by the rotation gear portion engaging with the transmission gear.
The automatic rotating-type turret device also has a hydraulic slide-drive mechanism comprising a fluid feed device for feeding a hydraulic slide-drive fluid; a clutch disengagement pressure chamber, into which the fluid is fed from the fluid feed device via a solenoid valve to slide the turret 3 in the shaft direction and unlock the clutch device 4; and a clutch pressure chamber, which is a slide gap that decreases in size when the turret 3 slides to disengage the clutch, wherein the solenoid value is switched so that the fluid is fed into the clutch pressure chamber, causing the turret 3 to slide in the return direction and the clutch device 4 to again lock the turret 3.
Work machinery of such description is subject to a large load during operation, particularly during lathe turning, in addition to the weight of the turret to which a plurality of tools are rotatably and switchably installed; and therefore a large clamping force is required. Therefore, as described above, there has been a need to use a hydraulic slide mechanism even for slidingly driving a turret in a conventional automatic rotating-type turret device, and a need to hold and maintain a clutch-engaged state, in which a secure lock is achieved by hydraulic pressure that generates the large clamping force, even after turret rotation concludes.
Also, while hydraulic pressure that generates the large clamping force (the turret slide-driving force in the reverse direction) is used to slide the turret in the reverse direction and lock the clutch device, the clutch device is configured so that the hydraulic pressure that generates the large clamping force slides the turret to unlock the clutch device. Therefore, in order to prevent the slide-driving force from being excessively large when the turret is caused to slide to enable rotation (i.e., to disengage the clutch), there is a need to design the clutch disengagement pressure chamber, into which the fluid is fed, to be as small as possible. Even in an instance where the clutch disengagement pressure chamber is designed to be significantly small, the slide-driving force may still be considerably large; as a result, when the sliding motion for disengaging the clutch narrows and fills the sliding gap, and surfaces come into contact, the pressing force due to hydraulic pressure may generate a large sliding friction resistance at the contact surface during clamp rotation.
In other words, the fact that hydraulic pressure is used to cause the turret to slide in the reverse direction and to hold and maintain the engaged state of the clutch device under pressure means that despite the device being capable of withstanding the large load generated during operation, there is also a possibility that a large slide pressing force due to the hydraulic pressure will result in a large sliding friction resistance being generated when the turret is turned after being caused to slide to disengage the clutch, resulting in more rapid wear and reduced durability as well as a possibility of galling during rotation.
Conventionally, in order to resolve such problems, there has been a need to provide a hydraulic pressure reducing mechanism or a similar mechanism, wherein a bypass channel becomes connected to the previously isolated clamp disengagement pressure chamber, the fluid is fed into a slide gap located opposite the clamp disengagement pressure chamber (i.e., the clutch pressure chamber) via the bypass channel, and the slide-driving force is reduced, when the feeding of the fluid into the clamp disengagement chamber exceeds a predetermined pressure or when the turret 3 slides in excess of a predetermined stroke, as shown, for example, in Unexamined Utility Model Application 57-149903.
This complicates the structure and control, and presents problems in that, for example, the device becomes more expensive and less adapted to mass-production, or that, for example, the unclamping speed when disengaging the clutch (i.e., to rotate the turret) has become slower.
Therefore, in order to minimize the use of hydraulics and limit resource consumption while also preventing excessive friction resistance from being generated during indexing when disengaging the clutch, there has been developed an innovative automatic rotating-type turret device (JP-A 2009-083070) that makes it possible to firmly lock and maintain a state in which the turret is in a clutch-engaged state so that it cannot rotate even using an air-pressure (i.e., pneumatic) slide-drive mechanism having an air feed device; and that has a wedge mechanism that makes it possible for the clutch position after sliding to adequately withstand the weight of the turret or a large cutting force even with use of a pneumatic slide-driving mechanism incapable of generating a driving force that can directly counter the slide cutting force (i.e., a force generated during lathe turning); thereby making it possible to remove hydraulics without adversely affecting turret rotation or the cutting function, and to reduce energy and resource consumption.
However, since the turret device has a configuration in which the turret is caused to slide in both directions along a rotation shaft portion, there is required a drive device for slidingly switching the turret between a locked position in which the clutch device is engaged and a rotatable position in which the clutch is disengaged, and a drive device for advancing or retracting the wedge portion so that the wedge portion engages with a wedge engaging portion when the clutch is in an engaged state, resulting in a structure that is still complex. Also, since the turret is of a “lift” type as described above, there is a higher risk of increased friction resistance during rotation and of ingress of dust or swarf, making it necessary to implement countermeasures and management measures, resulting in a complex structure.